package ${basePackage}.utils;

import javax.servlet.http.HttpServletRequest;

/**
 * @author ${author} on ${date}
 */
public class RequestUtil {
    private static final String UNKOWN_IP = "unknown";

    /**
    * 获取用户真实IP地址，不使用request.getRemoteAddr();的原因是有可能用户使用了代理软件方式避免真实IP地址,
    * <p>
    * 可是，如果通过了多级反向代理的话，X-Forwarded-For的值并不止一个，而是一串IP值，究竟哪个才是真正的用户端的真实IP呢？
    * 答案是取X-Forwarded-For中第一个非unknown的有效IP字符串。
    * <p>
    * 如：X-Forwarded-For：192.168.1.110, 192.168.1.120, 192.168.1.130,
    * 192.168.1.100
    * <p>
    * 用户真实IP为： 192.168.1.110
    *
    * @param request
    * @return
    */
    public static String getIpAddress(HttpServletRequest request) {
        String ip = request.getHeader("x-forwarded-for");
        if (ip == null || ip.length() == 0 || UNKOWN_IP.equalsIgnoreCase(ip)) {
            ip = request.getHeader("Proxy-Client-IP");
        }
        if (ip == null || ip.length() == 0 || UNKOWN_IP.equalsIgnoreCase(ip)) {
            ip = request.getHeader("WL-Proxy-Client-IP");
        }
        if (ip == null || ip.length() == 0 || UNKOWN_IP.equalsIgnoreCase(ip)) {
            ip = request.getHeader("HTTP_CLIENT_IP");
        }
        if (ip == null || ip.length() == 0 || UNKOWN_IP.equalsIgnoreCase(ip)) {
            ip = request.getHeader("HTTP_X_FORWARDED_FOR");
        }
        if (ip == null || ip.length() == 0 || UNKOWN_IP.equalsIgnoreCase(ip)) {
            ip = request.getRemoteAddr();
        }
        return ip;
    }
}
